1. Field of the Invention
The present invention relates to a resin mold semiconductor device, in particular, to a resin mold semiconductor device wherein a semiconductor chip and a frame are sealed in a molding resin.
2. Description of the Background Art
A resin mold semiconductor device is formed by securing a semiconductor chip, which is gained by dicing a silicon wafer on which a predetermined circuit pattern is formed, to a frame so that this is sealed in a molding resin.
Concretely, as shown in FIG. 23, first, a die bonding material 102 is applied to a frame 103. Next, a semiconductor chip 101 is mounted on frame 103 so as to be secured to frame 103 by means of die bonding material 102.
After that, semiconductor chip 101 and frame 103 are electrically connected (not shown) by means of wires, or the like, and semiconductor chip 101 and frame 103 are placed within a predetermined metal mold so that a molding resin is made to flow therein. Thus, a resin mold semiconductor device is gained.
However, a conventional resin mold semiconductor device has the following problem points. As described above, die bonding material 102 is used in order to secure semiconductor chip 101 to frame 103. Mainly, Pbxe2x80x94Sn-based solder or an epoxy-based resin is applied as die bonding material 102.
In particular, since Pb is included in the Pbxe2x80x94Sn-based solder, a securing method that does not use lead, that is to say, a securing method that does not use a die bonding material, is required in view of eliminating environmental problems.
The present invention is based on the above described requirements and a purpose thereof is to provide a resin mold semiconductor device wherein the semiconductor chip is secured to the frame without using a die bonding material.
A resin mold semiconductor device according to the present invention has a semiconductor chip, a frame part for mounting the semiconductor chip and a resin for sealing the semiconductor chip and the frame part. An airtight space of which the pressure is lower than atmospheric pressure is provided between the semiconductor chip and the frame part in order to secure the semiconductor chip to the frame part.
According to this structure, the semiconductor chip is secured to the frame part due to the differential pressure (negative pressure) between atmospheric pressure and the pressure within the airtight space that is created between the semiconductor chip and the frame part. Thereby, the semiconductor chip can be secured to the frame part without using a die bonding material in contrast to the conventional resin mold semiconductor. As a result, a die bonding material becomes unnecessary so that the utilization of lead, or the like, which is the cause of environmental pollution, can be eliminated.
Concretely, it is preferable to provide a sealing member placed between the semiconductor chip and the frame part so that the airtight space is created in a region surrounded by the sealing member.
Thereby, the airtightness of the airtight space can be secured.
In addition, it is preferable for the frame part to have a recess that becomes the airtight space and a frame side mirror surface portion formed in a portion that contacts the semiconductor chip part so as to surround the recess and it is preferable for the semiconductor chip to include a chip side mirror surface portion formed in a portion that contacts the frame side mirror surface portion.
In this case, since the frame side mirror surface portion and the chip side mirror surface portion contact each other so that the airtightness of the recess that becomes the airtight space is secured without using a sealing member and, thereby, the semiconductor chip can be secured to the frame part.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.